355GTS #3 Value?

Hi all, I found a Rosso Corsa black 355 GTS, (this would be my 3rd!) this one is a '97 that has had the valves and cats done in '98, and manifolds in '00 and a 30K done in 03. She has been driven 2K miles since the belts and I know she is due time wise. She is a 2 owner Ca. car, has about 21000 miles on it. What is this car worth if I do a 30K on her?